An experimental study on gas production from fracture-filled hydrate by CO 2 and CO 2 /N 2 replacement

•The thin layer of hydrate can be formed with ice layer by increasing its temperature.•The morphology of MH has an impact on gas production from MH by gas replacement.•CO2, CO2/N2 (3:1) and CO2/N2 (1:3) were selected for gas replacement.•The gas composition and pressure affected the replacement result together.•The ice around MH might inhibit the further decomposition of MH and gas replacement.